Thursday, December 18, 2014

Best essential oil products for bed bugs

If you're a pest management professional in the bed bug business, I suspect the last thing you might want to hear about is a good consumer treatment for bed bugs. But the latest study published the Journal of Economic Entomology by Changlu Wang's lab at Rutgers University may hold a little good news for everyone.

In the study results recently reported in PCT magazine, Narinderpal Singh, Wang and Richard Cooper identified two low-toxicity, over-the-counter products that are surprisingly effective against both bed bugs and their eggs. EcoRaider™ and Bed Bug Patrol™ are essential oil-based insecticides available both in retail stores and via the Internet.

One of the experimental setups used in the Singh et al paper inthe Journal of Economic Entomology. Laboratory tests are not always good predictors of what will work well under real world conditions; but they are most useful in identifying products less likely to work well.

The researchers looked at nine plant oil-based products and two detergents marketed for bed bug control. In the first evaluations bed bugs were sprayed directly with the 11 products, as well as with the pyrethroid standards Temprid® SC and Demand® CS. Only two of the consumer products provided greater than 90% control. A product called EcoRaider™ (1% geraniol, 1% cedar extract, and 2% sodium lauryl sulfate) provided 100% control of bed bug nymphs after 10 days. A second product, Bed Bug Patrol™ (0.003% clove oil, 1% peppermint oil, and 1.3% sodium lauryl sulfate) provided 91-92 percent mortality after 10 days in two trials. These essential oil products were slower than the professional insecticide Temprid® SC, but after 10 days they provided the statistically same control as Temprid®.

We all know the toughest life stage of bed bugs to kill is the egg. Singh et al. applied each of the sprays directly to exposed 2-3 day-old eggs. EcoRaider™ controlled 86% of eggs, better than any other product, including the professional standards which gave less than 17% control.

Of course a good insecticide should not only kill on direct contact, but should leave a residue that continues to kill, and not repel, after it dries. Singh and colleagues pitted EcoRaider™ and Bed Bug Patrol™ against the two pyrethroids by confining bed bugs for five minutes on one-day old residues on cotton fabric. They then removed the bugs, placed them in clean dishes and observed. After ten days, EcoRaider™ and Bed Bug Patrol™ provided an impressive 93% mortality, equivalent to Temprid® SC, and significantly better better than Demand® CS. However when bed bugs were allowed to choose between resting on treated or untreated surfaces, the two professional products were significantly better.

So don't dump your Temprids, Transports and Tandems just yet. Bed bugs always have a choice where to rest and walk in the real world, and these results suggest that when given a choice they might avoid spots treated with plant-oil products. And even the researchers admit that all spray exposures in this test were applied under ideal conditions. It's likely that results in the field, where bed bugs are almost always protected in cracks and crevices of furniture and bedding, will not be as good. Perhaps most importantly, even the best bed bug treatments miss directly contacting all bed bugs. Hence residual control is very important and rightly remains the holy grail of bed bug control. Today's modern insecticides may not always excel at long-term residual control of resistant bed bugs; but they are likely to be better than the best essential oil-based insecticide. The plant oil-based sprays in this test were only aged for a day, and given the volatility of plant oils I would not expect them to last much longer.

Nevertheless, low-toxicity "organic" pesticides have established a strong niche in the professional pest control business today. I applaud the efforts of the Rutgers researchers in sifting through the many "natural" products vying for bed bug market share. Singh et al's work may not be the last word on the subject of which green products work and which don't; but the methodology appears sound and the work thorough. Based on what I read in the paper, if I were looking for a green insecticide to supplement my bed bug program (even one that was available to consumers), I would take a hard look at their top two performers.

93% mortality in the world of insecticide resistant bed bugs is pretty good, especially on eggs which are difficult to kill. There are very few, perhaps no, products which would consistently achieve 100% mortality. Hence the need for an integrated approach to bed bug control (using multiple control methods) and for followup visits.

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About Me

I have served as entomology specialist for Texas AgriLife Extension since 1989. I get to work with, and for, a bunch of great people including pest management professionals, school facilities managers, extension volunteers, researchers and other extension professionals. My areas of specialty center on research on insects affecting man including spiders, scorpions, fire ants, termites and others. My program also focuses on training school maintenance professionals in principles of integrated pest management (IPM). Our goal is to make schools healthier, cleaner places to study and live.